In the field of speech recognition, the problems associated with error detection and correction vary according to the specific application and the situations and settings associated therewith. In a quiet office, for example, the user of a voice dictation application may rely on an active display in the form of a computer monitor to inform him/her of any errors in speech recognition. The same user may then correct any such errors with a computer keyboard. Alternatively, some applications permit a user to verbally select and correct text so displayed.
Drivers of automobiles find themselves in different situations. With both eyes and hands occupied with the task of driving, a driver may not always rely on an active display and keyboard for error detection and correction. At least one attempt at addressing this problem, Ishii et al., U.S. Pat. No. 6,067,521, entitled Interrupt Correction Of Speech Recognition For A Navigation Device, relies on relaying to the user a generated speech associated with a geographic location selected by the user for travel. If the user verbally enters a new location during processing of the first location or within a set timeframe, the previous entry is forgotten and the new one is taken instead.
Special problems, however, face the law enforcement officer attempting to input license plate information for search in a database. Recognition error rates remain high, particularly in noisy conditions frequently experienced by such officers. Common sources of noise include sirens, radio chatter, screeching tires, horns, and even gunfire. Emotional factors may also affect the quality of the speech (e.g. stress) making it more difficult to recognize. Adding to the difficulty of the situation, officers cannot always acquire the entire license plate information (including state, year and number) all at once. They must instead physically maneuver to facilitate visual inspection and acquisition of a few characters at a time. An officer attempting to enter a license plate number under the method taught by Ishii et al., for example, might first read in two characters of the plate. Then, upon pausing, the officer might read in a third character and replace the first two characters with the third character, thereby foiling entry of the data. Alternatively, under the same method, the officer may attempt to enter the entire plate at once and rely upon flawless speech recognition. Such flawless speech recognition remains highly unlikely under the adverse conditions frequently experienced by officers. Therefore, addressing the special needs for efficient, safe and reliable data entry by voice under adverse conditions remains the task of the present invention.